# 利用map和reduce编写一个str2float函数，把字符串'123.456'转换成浮点数123.456：
from functools import reduce
def str2float(s):
    n = s.index()
    integerPart = map(int,[x for x in s[:n]])
    decimalPart = map(int,[x for x in s[n+1:]])
    floatingPoint = reduce(lambda x,y:x*10+y,integerPart)+reduce(lambda x,y:x*10+y,decimalPart)/(10 ** len(decimalPart))
    return floatingPoint


print('str2float(\'123.456\') =', str2float('123.456'))
if abs(str2float('123.456') - 123.456) < 0.00001:
    print('测试成功!')
else:
    print('测试失败!')